Latch means for step-up mechanism



March 29, 1966 H. SEIDEN LATCH MEANS FOR STEP-UP MECHANISM 2 Sheets-Sheet 1 Filed Jan. 13, 1964 Fig.

March 29, 1966 H. L. SEIDEN 3,242,745

LATCH MEANS FOR STEP-UP MECHANISM Filed Jan. 15, 1964 2 Sheets-Sheet a INVENTIOR. fi /m/vl. J/AEW United States Patent 3,242,746 LATCH MEANS FOR STEP-UP MECHANISM Herman L. Seiden, Chicago, Ill., assignor to Lion Manufacturing Corporation, Chicago, 11]., a corporation of Illinois Filed Jan. 13, 1964, Ser. No. 337,346

- 14 Claims. (Cl. 74142) This invention pertains to step-by-step pawl and ratchet mechanisms sometimes referred to as step-up mechanisms or steppers, especially when used in conjunction with dial or drum type visual indicators or read-out means or rotary stepping switches, wherein a main shaft element is advanced angularly step-by-step as the result of actuation of driving movements of a pawl acting in the teeth of a ratchet wheel coupled with said shaft.

The driving pawl for such devices is commonly reciprocated by a solenoid; and a holding do-g releasably engages in the ratchet teeth to hold the gain of the wheel and may be released by another reset solenoid, the wheel storing energy in a return spring capable of turning it back to a starting position when the holding dog is released. Such return springs build up a significantly increased resistive force to the driving effort of the advancing pawl, particularly when the wheel must be turned through a full revolution or more, and accordingly it becomes necessary to provide a driving solenoid with sufficient power to assure accurate stepping near the end of the wheel travel, as well as in the initial phases thereof, and this results in an initial driving displacement of the advancing pawl which can be so vigorous before the return spring resistance builds up that the driving pawl may have a tendency to rebound and effect double steps, especially when the stepping action is rapid, this tendency also involving the holding dog which may not have time to seat fully before an additional unwanted step or fractional step is effected.

The present improvements provide a latching means associated with the holding dog mechanism and operative to latch the driving pawl from dislodgement from the ratchet teeth from any cause, such as rebound or partial secondary steps or fraudulent interference with the norrnal movements of the pawls or dogs, and in general to provide a latching means controlled by the holding mechanism and operable to prevent escape of the driving pawl from the ratchet teeth at any time excepting when the driving pawl is being displaced in stepping or resetting action.

The aforesaid objects and the improvements resultant therefrom are especially advantageous when used in conjunction with a type of stepper disclosed in U.S. Patent No. 2,895,340 to Nicolaus, wherein the driving pawl and the holding dog have cooperative formations adapted to interlock when the reset solenoid is energized and both the pawl and dog are raised from the ratchet teeth to free the wheel for return travel, the feature being that the interlock continues indefinitely until the first new advancing step is taken by the driving pawl to break the interlock, so that the device always starts a new cycle from an initial condition in which the pawls or dogs are wholly disengaged from the ratchet teeth and are restored to operative engagement therewith as a function of any first or starting operating pulse. It is to be understood, however, that the presently disclosed improvements are directed to a means for latching the driving pawl against malfunction in double stepping and the like, and such improvements are by no means limited to use in conjunction with the lock-out features of the Nicolaus patent, but may be employed usefully in combination with any stepping mechanism utilizing a driving 3,242,746 Patented Mar. 29, 1966 pawl and holding dog arranged in an operative adjacency analogous to that described hereinafter.

Additional objects and aspects of utility relate to details of the construction and coaction of the components of the preferred embodiment described hereinafter in view of the annexed drawings in which:

FIG. 1 is an elevational view of a step-up mechanism of the class described;

FIG. 2 is a fragmentary view of the mechanism of FIG. 1 with parts shown in operating conditions different from those of FIG. 1;

FIG. 3 is a fragmentary perspectvie view of the holding dog means and associated latching means and parts of the driving pawl;

FIG. 4 is an exploded perspective arrangement of parts seen in FIG. 3.

The embodiment depicted in FIG. 1 comprises a base plate 10 upon which is journalled a shaft 11 having affixed thereto a ratchet wheel 12 provided with a helical return spring 13 coiled upon an exposed portion of the shaft and having a free end portion 14 projecting for anchorage upon the pivot pin 42 for certain holding dog structures to be described.

Pivoted upon a pin 16 staked into the base plate is a long drive lever 17 having one of its ends pivotally connected as at 18 to the plunger 19 of a driving solenoid 20.

The driving lever 17 includes a channel-shaped midsection 17A traversed by the pin 16 and having an offset upper extension 17B in which is fixed a pivot pin 23 upon which floats a driving or advancing dog 25 including a pawl portion 26 disposed to engage in the ratchet teeth and be reciprocated responsive to oscillatory motion of the driving lever as aforesaid, a long traction spring 28 being attached at one of its ends to an ear 29' on said dog to pivot the latter in a direction tending to thrust said pawl portion always into said teeth, as illustrated in FIG. v2, which depicts the driving pawl portion pressed down into the teeth in readiness for an advancing stroke responsive to attraction of the plunger 19 as aforesaid, it being understood that the driving stroke of the pawl is actually the return stroke, toward the right, under urgence of the spring means 28, while the movement of the pawl responsive to the attraction of plunger 19 retracts the pawl toward the left a distance of one ratchet tooth and further tensions said spring for the tooth-advancing stroke.

Assuming that the ratchet wheel has been stepped a desired distance or number of times, the gain of the wheel will be held as a result of engagement of the holding dog means 34 in said teeth in the manner depicted in FIG. 2; and in order to restore the wheel to its starting position, the release solenoid 32 will be energized to attract its plunger 33 and thereby raise the offset pawl portion 34A from the teeth and'into the elevated position shown in FIG. 1.

It will be observed from FIG. 2 that the holding dog means includes an elongated nose portion 35 having formed as a part thereof a locking notch 36 adjoining an arcuate gliding land 37, and further, that the driving pawl has an upwardly offset and angled armportion 23A disposed to overlie said nose portion and gliding land of the holding dog in such manner that when the dog is elevated as aforesaid the land glides against the angled part of the driving pawl and elevates the latter until said angled part falls behind the notch 36, with the result that both the driving pawl and the holding dog become mutually interlocking in the elevated position depicted in FIG. 1, and meanwhile the return spring 13 turns the ratchet wheel back to starting position, which in the embodiment shown, may be determined by the engagement of a stop lug 39 on the underside of the wheel with a stiff spring buffer and stop blade 40 fixed on a bracket on the base plate.

The aforesaid lock-out condition of both dogs will persist until the driving pawl takes its first step following any release or reset operation producing such locked-up condition, it being apparent that, when the driving pawl is retracted toward the left, it will break the interlock with the holding dog at notch 36, so that the holding dog may drop again into holding engagement with the ratchet teeth.

The structural and functional characteristics of the step-up mechanism thus-far described are substantially thoseset forth in the aforesaid Nicolaus patent, the improve'rnents of the present disclosure relating particularly to changes in the holding-dog means incorporating a novel latching mechanism controlled thereby and by means of which certain malfunctions of the driving dog or pawl are prevented.

The improved structures are best described in view of FIG. 4 wherein the parts are shown in perspective in approximately correlative operating positions, attention being called to the holding dog 34 and the radial tail portion 34X thereof, which is free-ended or cut off, whereas in the Nicolaus patent the corresponding tail structure continues integrally into pivotal connection with the plunger of its releasing solenoid, with the result that the dog in the patent is pivotally joined directly and positively to the solenoid plunger, this not being the case, however, with the present construction because the dog means 34 simply floats upon its pivotal axis afforded by the pin 42, suitably staked into the base plate and serving also as the pivotal mounting for a special, disjoined, actuating lever 50.

Means for imparting reset and release action to the holding dog comprises the special dog-actuating lever 50 having an elongated radial extension 51 pivotally connecting by pin means 52 to the plunger 33 of the release solenoid, as in FIG. 1, said lever being pivotally mounted upon the pin 42 in interfitting relationship with the hold ing dog, said lever having an offset yoke portion 54 com prising opposite arms 55, 56 pierced to engage said pivot pin 42 and also pierced close to the bight of the yoke to receive a spring pin 57 supporting a latch spring 58.

The radially-extending portion of the actuating lever is provided with a pair of opposite tabs 59A, 59B struck up along its side margins to provide a form of disjoined or impositive yoke coupling with the holding dog, the tail 34X of which extends radially from the pivot pin 42 in close proximity to the radial part of the actuating lever so as to lie in between said tabs.

The width of the dog tail 34X in respect to the spacing between the two lever tabs 59A, 59B is such as to allow a limited freedom of movement of the dog relative to the actuating lever, and vice versa, in order that the dog may move slightly at times when the solenoid plunger is in normal position, for purposes to appear.

Since the holding dog 34A must yield or escape as the ratchet wheel advances tooth by tooth, while the latching nose 64 must be urged constantly downwardly for engagement upon the driving pawl, the impositive coupling afforded by the tail extension 34X and its slightly lo-ose fit in between the coupling tabs 59A, 59B permits sufiicient relative movement of the holding dog during the escape ment operations thereof without disturbance to the latching nose. The magnitude of such relative movement is related to the depth of the ratchet teeth and in the example shown would be, for example, of the order of about 34 inch for a ratchet wheel of about 3-inch diameter and tooth depth of about A; inch, and radial length of the which the driving pawl is pivoted in a clockwise sense to urge its pawl part 26 down int-o the ratchet teeth while the holding pawl means is pivoted in the reverse or counterclockwise sense to dispose its pawl part 34A in said teeth, the latter spring action being transmitted through the tail and tab coupling means 34X-59A, to elevate the release solenoid plunger 33. Thus, when the plunger is attracted electromagnetically, the holding do'g portion 34A is raised free of the teeth, and the gliding land 37 on said dog bears up upon the extended pawl portion 23A of the driving pawl to elevate the latter and produce the holding interlock at notch 36, as described, whereby the two dogs or pawls are held in mutually sustaining inoperative condition until such time as the driving pawl means is actuated again, either by pulsing the driving solenoid 20 to cause sufficient movement of the driving pawl to break the interlock at 36, or by a manual releasing operation in which the operator presses upon the finger extension 25F of the pawl member to produce the like result.

Means for latching the driving pawl in it's engagement in the ratchet teeth in certain positions of the pawl, comprises the peculiarly-shaped latch lever 60 depicted in FIG. 4 and consisting of a main arm portion 61 pierced to provide a pivot hole 62 engaging with the secondary pivot pin 57 carried by the yoke of the actuating lever, said main arm portion of the latch lever having a lug 63 struck out to be engaged by a free end portion 58A of the latch spring 58 which urges the latch lever in a clockwise sense relative to the actuating lever and the copivoted holding dog means. I

The free end or nose 64 of the latch lever constitutes a pawl-blocking latch means adapted to overlie the later-' ally-offset portion of the driving pawl part 26 in the manner shown in FIG. 3, when the parts are in a condition of rest corresponding substantially to the termination of a driving stroke of this pawl with the dog 34A in holding condition, as depicted also in FIG. 2, it being observed, however, in FIG. 1 that when both the driving pawl and holding dog are in the elevated or released condition, as when the solenoid 32 is energized, the latching lever nose 64 and blocking dog leg 65 are displaced toward the right into the dotted-line position of FIG. 1, owing to the attachment by pin 57 to the yoke part of the actuating lever, so that the driving pawl is free to move upwardly into the interlocked position previously described, as in FIG. '1.

Means for preventing dislodgment of the latching nose 64 from its normal blocking position above the driving pawl comprises the provision of an abutment lug 66 projecting laterally from the base plate 10 adjacent a clearance opening on window 67 punched into said plate to enable the free end of the driving pawl to project closely into and through the plane of the plate so that there will be no critical tolerances needed to maintain the moving pawl parts in cooperative alignment.

Projecting ang'u-larly beneath the blocking nose 64 of the latching lever is a dog-leg formation affording a catch member 65 acting in the manner of a hook beneath said block-ing lug 66, it being apparent that any upward or lifting force tending to dislodge the driving pawl up wardly from the ratchet teeth will be blocked by the nose portion 64, and such effort will be transmitted into the dog-leg catch projection 65 to lift the same against the lug 66, which in turn will completely resist any elevating movement of the latch lever nose 64 from pawllatching or blocking condition, and therefore will prevent any escape of the driving pawl from the teeth. The rocking motion imparted to the latch lever 60 on movement of the holding dog structure into release condition, will be sufficient to remove the latching nose 64 from the path of the driving pawl so that the latter may rise into the interlock position, but the dog-leg projection 65 will simply be shifted toward the right beneath the abutment lug 66 without wholly departing from beneath such lug.

When both pawl or dog parts 26 and 34A are down in the ratchet teeth, as in FIG. 2 and the corresponding condition of these parts. as shown in FIG. 3, any force tending to unseat the driving pawl 26 from the teeth, that is to say, any force tending to cause upward escape of the pawl portion 26 away from the teeth, is resisted by the blocking action of the overlying latch projection 64. For example, in this latter condition, pressure on the finger lever 25F of the driving pawl will be inelfectual to raise the pawl from the teeth, as will any elevating force applied directly to the free end portion of the pawl 26, tending to lift the driving pawl from the teeth in the lowered or normal position of the holding pawl means, and resulting for example from rebound effects, overstroking and transient reactive effects produced by very fast and energetic actuations of the driving lever system.

Step-up devices of the class described are commonly employed in coin-operated vending and amusement apparatus, and fraudulent practices include attempts to interfere with normal operation of these mechanisms as by inducing extra steps or freeing the dogs by imparting jarring blows t the containing cabinets at times when the ratchet wheel is being advanced whereby to induce double stepping, the latching of the driving pawl by the means and in the manner described being useful to discourage such practices as well as minimize faulty stepping from purely operational conditions, as described.

I claim:

1. In a step-up mechanism having :a ratchet wheel, a driving pawl for said wheel and means for actuating said pawl to advance said wheel stepby-step, together with spring means acting on the wheel to return the same from advanced to a starting position and a releasable holding dog means cooperable with the wheel tohold the same in advanced position, improvements comprising, namely: means pivotally mounting and yieldingly urging the holding dog in cooperative relation to said wheel -for movement into and out of holding engagement therewith; an electromagnetic solenoid including a plunger for pivoting said holding do-g means into and out of holding engagement with the ratchet wheel; a dog-actuating lever oo-pivoted with said holding dog means and having an impositive driving interconnection with said solenoid plunger for actuation to oscillate the same about its pivotal axis and comprising an actuating lever having a part extending radially of said axis between the later and the connection thereof with said plunger, and 'said dog means having a part likewise extending radially of said axis and co-directionally along side said radiallyextending part of the actuating lever; and means carried by said actuating lever on opposite sides of said radiallyextending part of the latter to engage an opposite side portion of the radially-extending part of the dog means responsive to oscillation of the actuating lever by actuation of said plunger whereby to impart directionally corresponding movement to the holding dog means, depending upon the direction of movement of the actuating lever by said plunger, whereby said impositive driving interconnection is such as to permit a limited amount of oscillatory escape movement of the holding dog means independently of said link and plunger during movement of the ratchet wheel by said driving pawl; a latch lever pivotally carried by said actuating lever and disposed to overlie a part of said driving pawl when the latter is disposed a predetermined distance toward and into ratchet-advancing position with the holding dog means in substantially holding engagement with said ratchet wheel, whereby to prevent displacement of the driving pawl from engagement with the teeth of the wheel by any movement in a direction approximately radially away from the wheel.

2. In a ratchet step-up device of the type including a toothed ratchet wheel, a driving pawl which is both reciprocable to advance the wheel, and pivotable out of engagement with the teeth of the wheel, and a holding means including a holding dog which is pivotable into and out of holding engagement in the teeth of the wheel, improvements comprising, namely: means for latching the driving pawl against motion in a direction out of engagement with the teeth approximately radially of the wheel, said means comprising a holding dog mechanism including a holding dog pivotable thereby as aforesaid; a latch lever pivoted on a part of said holding dog mechanism and including a blocking portion disposed to overlie a part associated with the driving pawl to block movement of the pawl in the radial direction aforesaid at least at times when the holding dog is in a predetermined range of movement into and out of holding engagement with said teeth, said mechanism moving said latching lever and causing withdrawal of the blocking portion from blocking relation to the driving pawl part when the holding dog moves a predetermined amount in a direction out of holding engagement with said teeth, said blocking portion being arranged and constructed when in blocking position to permit free reciprocable movement of the driving pawl to advance the wheel.

3. In a step-up mechanism of the type having a rotatable ratchet wheel, a driving pawl which is movable pivotally into and out of driving engagement with the teeth of said wheel and also reciprocable to drive with said teeth to advance the wheel one step at a time, together with releasable holding means for preventing retrogression of the wheel, improvements consisting in: a combination latching and holding means comprising a holding dog pivotable in wheel-advance escape action and also into and out of holding and releasing engagement with the teeth of said wheel, and means for pivoting the dog in release action, together with a latch part movable by the pivoting means into and out of blocking relation with said driving pawl responsive to dog-releasing actuation thereof; said latch part being disposed in blocking relation with the pawl when the holding dog is disposed in holding relationship to said teeth so as to block movement of the pawl in .a sense generally radially away from said teeth while freely permitting reciprocatory drive movement of said pawl; and means yieldingly urging said latch part into substantially constant blocking relationship with the driving pawl as aforesaid while the holding dog is engaged with the ratchet wheel but permitting escape motion of the holding dog tooth by tooth responsive to advancing movement of said wheel.

4. In a stepping mechanism including a rotatable ratchet tooth wheel, a reciprocable driving pawl engageable with the teeth of said wheel in reciprocatory action to advance the wheel in one direction, means tending to turn the wheel in an opposite retrograde direction from advanced position; said driving pawl being pivotable into and out of operative engagement with said teeth thereof, pendently of the reciprocatory driving action thereof, and means for holding the gain of the wheel including a releasable holding dog and means for releasing same; improvements comprising: a holding dog mechanism including a dog and means pivotally mounting the same for dogging engagement and action with the wheel teeth to permit advance of the wheel but prevent retrogression thereof, and also for movement to and from operative holding engagement with said teeth; and means for preventing operative disengagement of the driving pawl with said teeth at times when the dog is out of operative engagement with said teeth, said last-mentioned means comprising first means movable to and from a blocking position relative to said pawl for blocking the same from disengagement with the teeth while permitting driving movement relative to said teeth; and second means having operative connection with said first means and said holding dog mechanism for actuation by the latter to move the first means from blocking position substantially in step with movement by said mechanism of the dog from holding engagement as aforesaid, said first means being arranged and constructed to offer no interference with driving movement of said pawl when engaged in the ratchet teeth.

5. Mechanism according to claim 4 further characterized in that said driving pawl and holding d-og mecha nism have cooperating parts serving, on movement of the holding dog out of holding engagement with the ratchet teeth, to move the driving pawl likewise out of operative engagement with said teeth, said first means for blocking the pawl being moved from blocking relation to the pawl in advance of the commencement of movement of the driving pawl out of operative engagement with the wheel teeth.

6. Mechanism according to claim 5 wherein said holding dog mechanism includes lever means operable to move the holding dog to and from holding engagement as aforesaid, together with a solenoid having a plunger movable thereby to motivate said dog mechanism in dogreleasing action at least; and means providing a loose driving interconnection between said plunger and lever means and operable to transmit driving power to the latter while permitting a limited amount of movement of the dog relative to said teeth in wheel-advancing escape action independently of said driving interconnection so as not to load or be loaded thereby.

7. In a pawl and ratchet mechanism, the combination with a rotatable ratchet wheel spring-urged to a normal starting position, of a driving pawl pivoted to engage and disengage with the teeth of said wheel and reciprocable to advance said wheel in steps, tooth-by-tooth, holding means including a releasable holding dog pivoted to engage and disengage with said teeth, first lever means for moving said dog, and a latch lever carried by said first lever means and having a latching part disposed to overlie said driving pawl in the position of the latter at all times drivingly engaging in said teeth including the commencement and termination of the driving stroke thereof, whereby a block dislodgement of said pawl from said teeth in a direction approximately radially of said wheel and teeth thereon, saidlatching part being effectively displaced from said blocking relation to the driving pawl cooperatively with releasing operation of the holding dog at a time when the holding dog has been moved a predetermined amount in a direction to disengage said ratchet teeth, and means on said driving pawl coacting with further means part of said holding means to cause the pawl to disengage the teeth substantially in step with disengagement of the holding dog from said teeth.

8. Mechanism according to claim 7 further characterized by the provision of electromagnetic means for actuating the holding means to move the holding dog as aforesaid; and means providing an impositive driving coupling between said holding dog and said electromagnetic means whereby to permit a limited freedom of toothdisengaging escape motion of the holding dog during advance of the wheel without effective transmission of any of the corresponding motion to said actuating means.

9. In a step-up mechanism having a toothed ratchet wheel and a stepping pawl which is both reciprocable and pivotable relative to the teeth of said wheel, and a holding dog mechanism including dog means which is pivotable at least in respect to the teeth of the wheel in both advancing escape and full releasing action, improvements comprising: the combination with said holding dog mechanism of a latch lever pivotally attached to a part thereof and movable by said mechanism into and out of blocking relation with said stepping pawl particularly in the range of movement of the later which includes its positions approaching and at the end of its stepping movement, provided that said holding dog is also in holding engagement with the teeth of the wheel, the blocking action of said latch lever being limited to movement of the stepping pawl in a direction approximately radially away from the wheel and teeth thereon and having no effect upon the reciprocatory stepping movement of the pawl.

10. In a step-up device having a toothed ratchet wheel, stepping mechanism including a stepping pawl, and hold ing mechanism including a holding pawl cooperable with the teeth of said wheel with both pawls respectively movable in a sense approximately radial of the wheel axis to engage in and withdraw from said teeth, the stepping pawl being also movable in a direction approximately tangential of the teeth to step the wheel, improvements for locking the stepping pawl from escape from the teeth in said radial sense comprising: a latching lever pivotally mounted adjacent said holding pawl and including a blocking part disposed to overlie a part of the stepping pawl when the latter is engaged down in said teeth and the holding pawl is likewise engaged in holding condition in said teeth, whereby said blocking part prevents the stepping pawl from escaping radially out of said teeth, and means operatively interconnecting said latching lever with said holding pawl mechanism for cooperation such that said holding pawl when moved toward wheel-releasing position radially out of said teeth also moves said latching lever and effects withdrawal of said blocking part from blocking relation to the stepping pawl so that the latter may be free to move radially out of the teeth.

11. A construction according to claim 10 further characterized in that said latching lever has an additional blocking part and said step-up device includes a member stationary relative to said wheel and pawls and disposed to overlie said additional blocking part to prevent movement of the latter and said latching lever more than a small predetermined amount in a direction radially away from the wheel axis but permits the aforesaid movement of the latching lever with the holding pawl for purposes of withdrawing the first-mentioned blocking part from blocking relation with the stepping pawl, whereby the latching lever is prevented from being moved to free the stepping pawl for radial movement by forces other than those causing movement of the holding pawl in wheel-releasing action by cooperation with the pawl mechanism, as aforesaid.

12. The construction set forth in claim 11 in which there is provided an electromagnetic means for actuating the holding pawl mechanism and imparting wheel-releasing movement to said holding pawl in the radial direction as set forth, and said electromagnetic means includes a driving member and an actuating member moved thereby for imparting said wheel-releasing movement to the holding pawl, said actuating member and said holding pawl mechanism having cooperating coupling means providing a loose driving coupling therebetween permitting a limited freedom of movement of small degree of the holding pawl with respect to the actuating member sufficient to permit the holding pawl to move in wheel-advancing escapement action relative to the ratchet teeth but insufficienltl to permit escape of the stepping pawl from said teet 13. In a pawl and ratchet wheel mechanism including a driven pawl having two movements, one to engage and drive in the teeth of a ratchet wheel and another to disengage said teeth; and a holding and releasing mechanism including a holding dog also having at least two movements, one to engage holdingly in said teeth to hold the gain of the wheel and another to disengage said teeth to release said wheel, improvements comprising: means for preventing disengagement of the driving pawl from the teeth in a certain range of movement of the holding dog relative to said teeth, said means comprising a latch member and means mounting the same for movement to and from blocking and released positions in relation with the driving pawl such that in the blocking position the driving pawl is prevented from drivingly disengaging the teeth while being free to move in driving coaction therewith; and in the released position the latch member is displaced from the blocking position to permit the movement of the driving pawl which disengages the teeth;

means normally yieldingly urging the latch member to said blocking position; and means providing a driving interconnection between parts of said holding and releasing mechanism and said latch member and effective to move the latter to the released position responsive to movement of the holding dog by the holding and releasing mechanism a predetermined, amount in the direction of disengagement with said teeth.

14. Apparatus as defined in claim 13 further including electromagnetic actuating means for actuating said releasing and holding mechanism to effect movement of the holding dog in said teeth-disengaging direction, and means part of said releasing and holding mechanism providing a loose driving interconnection with said actuating References Cited by the Examiner UNITED STATES PATENTS 2,281,262 4/ 1942 Breitenstein 74-142 2,452,030 10/ 1948 Hughes 74-142 2,864,260 12/1958 Nicolaus 74142 2,895,340 7/1959 Nicolaus 74158 X BROUGHTON G. DURHAM, Primary Examiner. J. A. MARSHALL, Assistant Examiner. 

1. IN A STEP-UP MECHANISM HAVING A RATCHET WHEEL, A DRIVING PAWL FOR SAID WHEEL AND MEANS FOR ACTUATING SAID PAWL TO ADVANCE SAID WHEEL STEP-BY-STEP, TOGETHER WITH SPRING MEANS ACTING ON THE WHEEL TO RETURN THE SAME FROM ADVANCED TO A STARTING POSITION AND A RELEASABLE HOLDING DOG MEANS COOPERABLE WITH THE WHEEL TO HOLD THE SAME IN ADVANCED POSITION, IMPROVEMENTS COMPRISING, NAMELY: MEANS PIVOTALLY MOUNTING AND YIELDINGLY URGING THE HOLDING DOG IN COOPERATIVE RELATION TO SAID WHEEL FOR MOVEMENT INTO AND OUT OF HOLDING ENGAGEMENT THEREWITH; AN ELECTROMAGNETIC SOLENOID INCLUDING A PLUNGER FOR PIVOTING SAID HOLDING DOG MEANS INTO AND OUT OF HOLDING ENGAGEMENT WITH THE RATCHET WHEEL; A DOG-ACTUATING LEVER CO-PIVOTED WITH SAID HOLDING DOG MEANS AND HAVING AN IMPOSITIVE DRIVING INTERCONNECTION WITH SAID SOLENOID PLUNGER FOR ACTUATION TO OSCILLATE THE SAME ABOUT ITS PIVOTAL AXIS AND COMPRISING AN ACTUATING LEVER HAVING A PART EXTENDING RADIALLY OF SAID AXIS BETWEEN THE LATER AND THE CONNECTION THEREOF WITH SAID PLUNGER, AND SAID DOG MEANS HAVING A PART LIKEWISE EXTENDING RADIALLY OF SAID AXIS AND CO-DIRECTIONALLY ALONG SIDE SAID RADIALLYEXTENDING PART OF THE ACTUATING LEVER; AND MEANS CARRIED BY SAID ACTUATING LEVER ON OPPOSITE SIDES OF SAID RADIALLYEXTENDING PART OF THE LATTER TO ENGAGE AN OPPOSITE SIDE PORTION OF THE RADIALLY-EXTENDING PART OF THE DOG MEANS RESPONSIVE TO OSCILLATION OF THE ACTUATING LEVER BY ACTUATION OF SAID PLUNGER WHEREBY TO IMPART DIRECTIONALLY CORRESPONDING MOVEMENT TO THE HOLDING DOG MEANS, DEPENDING UPON THE DIRECTION OF MOVEMENT OF THE ACTUATING LEVER BY SAID PLUNGER, WHEREBY SAID IMPOSITIVE DRIVING INTERCONNECTION IS SUCH AS TO PERMIT A LIMITED AMOUNT OF OSCILLATORY ESCAPE MOVEMENT OF THE HOLDING DOG MEANS INDEPENDENTLY OF SAID LINK AND PLUNGER DURING MOVEMENT OF THE RATCHET WHEEL BY SAID DRIVING PAWL; A LATCH LEVER PIVOTALLY CARRIED BY SAID ACTUATING LEVER AND DISPOSED TO OVERLIE A PART OF SAID DRIVING PAWL WHEN THE LATTER IS DISPOSED A PREDETERMINED DISTANCE TOWARD AND INTO RATCHET-ADVANCING POSITION WITH THE HOLDING DOG MEANS IN SUBSTANTIALLY HOLDING ENGAGEMENT WITH SAID RATCHET WHEEL, WHEREBY TO PREVENT DISPLACEMENT OF THE DRIVING PAWL FROM ENGAGEMENT WITH THE TEETH OF THE WHEEL BY ANY MOVEMENT IN A DIRECTION APPROXIMATELY RADIALLY AWAY FROM THE WHEEL. 